This invention relates to an electron collimation system for electron arc therapy treatments and more particularly to the secondary and tertiary collimation devices for rotating electron beams for radiation therapy.
A fixed field collimator which makes use of the conventional jaw-type systems has been disclosed in U.S. Pat. No. 3,767,931, issued Oct. 23, 1973 to Norman H. Williams and assigned to the assignee of the present invention. Such systems, however, are far from adequate as an electron collimation system for electron arc therapy treatments because they are not designed either to allow for dose compensation in the sagittal plane for differing thickness of the patient's body above the target for irradiation nor to provide maximum safety to the patient.